Robert C. Randall, a glaucoma patient who formerly taught speech at Prince George's Community College, shook up drug enforcement officials in 1978 when he went to court to get permission to smoke marijuana to relieve the symptoms of his eye disease.

He won that battle, but now the nation's first legal "pot" smoker is having trouble convincing the British that marijuana has medicinal uses.

Randall, 39, was detained by British customs authorities in London last month shortly after he arrived at Heathrow Airport with 21 marijuana cigarettes. He declared the marijuana, calling it his medication; the British confiscated the cigarettes but did not arrest him.

"I feel the British government is restricting my ability to come to Britain by restricting my marijuana," said Randall, who is president of the Alliance for Cannabis Therapeutics and had been invited to London to address a drug policy seminar.

Randall, a District resident, said he notified British officials before his July 20 arrival and sought permission to import the marijuana and maintain his prescription for it. He said he planned to spend two weeks abroad -- visiting Scotland and his mother's birthplace in Wales -- but cut short his stay and returned to the United States July 24.

Randall smokes marijuana -- 10 cigarettes a day, seven days a week -- in a U.S. government-sanctioned effort to help stem the spread of his glaucoma and relieve pressure on the optic nerves of both eyes.

A former "light social user" of marijuana, Randall said he has built up a physiological tolerance for the drug and now gets no "high" from it.

A spokesman for the British Embassy here said that under British law marijuana has no recognized therapeutic or medicinal use. Randall said he may appeal Britain's handling of his case.

In the meantime, Randall said he is busy preparing for Drug Enforcement Administration hearings this fall on whether to reclassify marijuana formally to make it easier to use it medicinally. He said he expects his group to renew its push for national legislation allowing the drug to be used therapeutically.